Here is the useful iris care checklist developed by avid iris lovers, Leon and Norma Vogel, who have a lovely garden in Murrieta, California with their irises planted among many other flowering plants.
January and February
- Fertilize again for the Spring burst of blooms.
- Check for aphids that hid all winter at base of leaves.
- Discard all dead leaves and weeds.
- Check to see if all labels are properly set by proper iris clumps.
- Keep irises watered if a dry winter.
- Foliar feed for bigger and brighter colored blossoms.
March and April
- Look for first blooms in mid-March and all through April.
- Check for aphids and white fly and spray if they are seen.
- Water regularly if a dry winter.
- Make last foliar feeding for more flowers.
- Clean weeds and dead leaves.
- Give Japanese and Louisiana iris an application of an acid food -- a camellia-type fertilizer is good.
May and June
- Continue to enjoy lots of blooms into early June.
- Check to see if all the iris labels match their name (check bloom description)..
- Cut the bloom stalk near the ground when done blooming.
- Feed heavily (one tblsp. per rhizome) with 6-20-20 or similar mix when bloom season is over.
- Check for aphids near the rhizomes, also for leaf rust.
- Keep weeds and dead leaves removed.
- Do not neglect to water enough to keep them growing, but be careful not to over-water.
July and August
- Dig clumps that are over-crowded. Divide and share rhizomes with friends.
- Dig whole beds if necessary to thin the clumps.
- Be sure to add amendments to soil such as fertilizer, peat moss, compost, gypsum and new top soil.
- Rototill the soil well and allow to stand for a week if possible before planting new iris rhizomes.
- Feed (fertilize) at least 3 times yearly. Foliar feed in between for stellar results. Irises are heavy feeders.
- Irises can remain out of ground for 3 weeks or more before replanting. Keep dug rhizomes in cool dry place for storage.
- Replant rhizomes, the top 1/4 should be showing above the soil line to prevent rot and allow them to breathe.
- Trim the roots back to an inch when replanting-- they send out all new roots within a few weeks.
- Do not neglect to water enough to keep them growing. New beds require more water.
- Reblooming irises may surprise you with flowers in July-February.
September and October
- Complete digging and replanting of your irises.
- Fertilize again. Irises grow all winter long in Southern California. This differs from colder climates where you would want your irises to go dormant in the winter.
- Plant any new iris you may have purchased. Label your irises. Be sure mark in water-proof ink.
- Keep weeds under control. Check for aphids and white fly and spray with insecticidal soap, if necessary.
- Pull off and discard all dead leaves.
November and December
- If for some reason you didn’t get all the things done, it is not too late to fertilize or plant new irises.
- Pull weeds as necessary.
- Check for aphids often particularly if the winter is mild.
- Keep the beds clean of everything except growing iris.
- If you have reblooming iris, they need extra fertilizer and water. You can have iris blooms year-round if you include “reblooming” irises.